The Checkpoint Protein Rad24 of Saccharomyces cerevisiae Is Involved in Processing Double-Strand Break Ends and in Recombination Partner Choice

Abstract

Upon chromosomal damage, cells activate a checkpoint response that includes cell cycle arrest and a stimulation of DNA repair. The checkpoint protein Rad24 is key to the survival of a single, repairable double-strand break (DSB). However, the low survival of rad24 cells is not due to their inability to arrest cell cycle progression. In rad24 mutants, processing of the broken ends is delayed and protracted, resulting in extended kinetics of DSB repair and in cell death. The limited resection of rad24 mutants also affects recombination partner choice by a mechanism dependent on the length of the interacting homologous donor sequences. Unexpectedly, rad24 cells with a DSB eventually accumulate and die at the G₂/M phase of the cell cycle. This arrest depends on the spindle checkpoint protein Mad2.

ACKNOWLEDGMENTS

We thank the anonymous reviewers whose suggestions helped to improve our manuscript. We thank Jasper Rine, Rodney Rothstein, and Anat Krauskopf for the generous gift of strains and plasmids. We are grateful to Nurit Paz and Lilach Chen for excellent ideas and technical help. We also thank all the members of the Kupiec laboratory for helpful comments and support.

This work was supported by a grant to M.K. from the Israel Science Foundation.